Thin film inductive write heads used in magnetic recording disk drives have a lithographically patterned thin film coil formed on the trailing end of the head carrier or air-bearing slider. The region between the coil turns and the region between the coil and the air-bearing surface (ABS) of the slider is typically formed of organic photoresist material that has been baked at a high temperature to provide an electrically insulative property. This photoresist material that later becomes the electrical insulation material after high temperature baking is originally deposited between the coil turns and on top of the coil turns to provide a planar surface for the subsequent deposition of a layer of ferromagnetic material that becomes one of the pole pieces. The completed write head, including the outer pole piece, is covered with a dielectric insulator, such as alumina (Al.sub.2 O.sub.3), to encapsulate the complete head structure. However, the hard baked organic photoresist material beneath the alumina overcoat has a thermal expansion coefficient almost three times that of alumina. As a result, during the recording cycle, when heat is generated by the coil, the overcoat can delaminate and/or protrude past the ABS.
What is needed is an improved thin film inductive write head that minimizes this thermal mismatch of different materials, and a process for its manufacture that still allows for a planarized pole piece to be formed.